Guaranteeing the safety performance of chemical process units is the premise for the safety production of chemical enterprises.Only to have the system safety management of the whole life cycle of the process units can...Guaranteeing the safety performance of chemical process units is the premise for the safety production of chemical enterprises.Only to have the system safety management of the whole life cycle of the process units can operate the process systems under the state of controllable risk.展开更多
Using the dissipated energy as an essential parameter,the energy dissipative structure in pro- cess of fatigue damage of materials has been established.Through thermodynamic analysis for irreversible energy dissipatio...Using the dissipated energy as an essential parameter,the energy dissipative structure in pro- cess of fatigue damage of materials has been established.Through thermodynamic analysis for irreversible energy dissipation in fatigue damage process,the heat dissipative variations in cyclic loading process as well as in a cycle have been systematically studied on the basis of low cycle fatigue tests and infrared measurement of self-heating thermography.Meanwhile,the cyclic hysteresis energy and efficient energy dissipation (stored energy) have been proposed during fatigue damage process.展开更多
Nowadays, new retail formats have been growing rapidly in China. Looking into the different retail formats＇ development deeply, a quantitative method＇is proposed for comprehensive appraisal. The proposed method uses...Nowadays, new retail formats have been growing rapidly in China. Looking into the different retail formats＇ development deeply, a quantitative method＇is proposed for comprehensive appraisal. The proposed method uses the retail life cycle to structure the appraisal factors hierarchically as the criteria in the basic framework of the AHP, and obtains the weight of the criteria from ratio-scale matrices as well as the scores of the altemative retail formats from pairwise comparison matrices. And this method is applied to study the different developing level of three retail formats in Xi＇ an and their developing order is then gained.展开更多
Precipitation comes in various phases, including rainfall, snowfall, sleet, and hail. Shifts of precipitation phases, as well as changes in precipitation amount, intensity, and frequency, have significant impacts on r...Precipitation comes in various phases, including rainfall, snowfall, sleet, and hail. Shifts of precipitation phases, as well as changes in precipitation amount, intensity, and frequency, have significant impacts on regional climate, hydrology,ecology, and the energy balance of the land-atmosphere system. Over the past century, certain progress has been achieved in aspects such as the observation, discrimination, transformation, and impact of precipitation phases. Mainly including: since the1980s, studies on the observation, formation mechanism, and prediction of precipitation phases have gradually received greater attention and reached a certain scale. The estimation of different precipitation phases using new detection theories and methods has become a research focus. Avariety of discrimination methods or schemes, such as the potential thickness threshold method of the air layer, the temperature threshold method of the characteristic layer, and the near-surface air temperature threshold method,have emerged one after another. Meanwhile, comparative studies on the discrimination accuracy and applicability assessment of multiple methods or schemes have also been carried out simultaneously. In recent years, the shift of precipitation from solid to liquid(SPSL) in the mid-to-high latitudes of the Northern Hemisphere has become more pronounced due to global warming and human activities. It leads to an increase in rain-on-snow(ROS) events and avalanche disasters, affecting the speed, intensity, and duration of spring snow-melting, accelerating sea ice and glacier melting, releasing carbon from permafrost, altering soil moisture, productivity, and phenological characteristics of ecosystems, and thereby affecting their structures, processes, qualities, and service functions. Although some progress has been made in the study of precipitation phases, there remains considerable research potential in terms of completeness of basic data, reliability of discrimination schemes, and the mechanistic understanding of the interaction between SPSL and other elements or systems. The study on shifts of precipitation phases and their impacts will play an increasingly important role in assessing the impacts of global climate change, water cycle processes,water resources management, snow and ice processes, snow and ice-related disasters, carbon emissions from permafrost, and ecosystem safety.展开更多
This study reports a new model of an air standard Dual-Miller cycle(DMC) with two polytropic processes and heat transfer loss.The two reversible adiabatic processes which could not be realized in practice are replaced...This study reports a new model of an air standard Dual-Miller cycle(DMC) with two polytropic processes and heat transfer loss.The two reversible adiabatic processes which could not be realized in practice are replaced with two polytropic processes in order to more accurately reflect the practical working performance. The heat transfer loss is taken into account. The expressions of power output, thermal efficiency, entropy generation rate(EGR) and ecological function are addressed using finite-time thermodynamic theory. Through numerical calculations, the influences of compression ratio, cut-off ratio and polytropic exponent on the performance are thermodynamically analyzed. The model can be simplified to other cycle models under specific conditions, which means the results have an certain universality and may be helpful in the design of practical heat engines. It is shown that the entropy generation minimization does not always lead to the best system performance.展开更多
Software engineering is broadly discussed as falling far short of expectations. Data and examples are used to justify how software itself is often poor, how the engineering of software leaves much to be desired, and h...Software engineering is broadly discussed as falling far short of expectations. Data and examples are used to justify how software itself is often poor, how the engineering of software leaves much to be desired, and how research in software engineering has not made enough progress to help overcome these weaknesses. However, these data and examples are presented and interpreted in ways that are arguably imbalanced. This imbalance, usually taken at face value, may be distracting the field from making significant progress towards improving the effective engineering of software, a goal the entire community shares. Research dichotomies, which tend to pit one approach against another, often subtly hint that there is a best way to engineer software or a best way to perform research on software. This, too, may be distracting the field from important classes of progress.展开更多
As one of the largest human activities, World Expo is an important source of anthropogenic Greenhouse Gas emission（GHG）, and the GHG emission and other environmental impacts of the Expo Shanghai 2010, where around 5...As one of the largest human activities, World Expo is an important source of anthropogenic Greenhouse Gas emission（GHG）, and the GHG emission and other environmental impacts of the Expo Shanghai 2010, where around 59,397 tons of waste was generated during 184 Expo running days, were assessed by life cycle assessment（LCA）. Two scenarios, i.e., the actual and expected figures of the waste sector, were assessed and compared, and 124.01 kg CO2-equivalent（CO2-eq.）, 4.43 kg SO2-eq., 4.88 kg NO-3-eq., and 3509 m3 water per ton tourist waste were found to be released in terms of global warming（GW）, acidification（AC）,nutrient enrichment（NE） and spoiled groundwater resources（SGWR）, respectively. The total GHG emission was around 3499 ton CO2-eq. from the waste sector in Expo Park, among which 86.47% was generated during the waste landfilling at the rate of 107.24 kg CO2-eq.,and CH4, CO and other hydrocarbons（HC） were the main contributors. If the waste sorting process had been implemented according to the plan scenario, around 497 ton CO2-eq.savings could have been attained. Unlike municipal solid waste, with more organic matter content, an incineration plant is more suitable for tourist waste disposal due to its high heating value, from the GHG reduction perspective.展开更多
文摘Guaranteeing the safety performance of chemical process units is the premise for the safety production of chemical enterprises.Only to have the system safety management of the whole life cycle of the process units can operate the process systems under the state of controllable risk.
文摘Using the dissipated energy as an essential parameter,the energy dissipative structure in pro- cess of fatigue damage of materials has been established.Through thermodynamic analysis for irreversible energy dissipation in fatigue damage process,the heat dissipative variations in cyclic loading process as well as in a cycle have been systematically studied on the basis of low cycle fatigue tests and infrared measurement of self-heating thermography.Meanwhile,the cyclic hysteresis energy and efficient energy dissipation (stored energy) have been proposed during fatigue damage process.
基金This research was sponsored by Soft Science Foundation of Xi＇an （R200251） and Innovation Foundation for postgraduate students of NWPU （Z20040069）.
文摘Nowadays, new retail formats have been growing rapidly in China. Looking into the different retail formats＇ development deeply, a quantitative method＇is proposed for comprehensive appraisal. The proposed method uses the retail life cycle to structure the appraisal factors hierarchically as the criteria in the basic framework of the AHP, and obtains the weight of the criteria from ratio-scale matrices as well as the scores of the altemative retail formats from pairwise comparison matrices. And this method is applied to study the different developing level of three retail formats in Xi＇ an and their developing order is then gained.
基金supported by the Sub-theme of the Second Comprehensive Scientific Investigation of the Tibetan Plateau (Grant No. 2019QZKK020109-1)the National Natural Science Foundation of China (Grant Nos. 42261026 & 42161025)the Open Foundation of Xinjiang Key Laboratory of Water Cycle and Utilization in Arid Zone (Grant No. XJYS0907-2023-01)。
文摘Precipitation comes in various phases, including rainfall, snowfall, sleet, and hail. Shifts of precipitation phases, as well as changes in precipitation amount, intensity, and frequency, have significant impacts on regional climate, hydrology,ecology, and the energy balance of the land-atmosphere system. Over the past century, certain progress has been achieved in aspects such as the observation, discrimination, transformation, and impact of precipitation phases. Mainly including: since the1980s, studies on the observation, formation mechanism, and prediction of precipitation phases have gradually received greater attention and reached a certain scale. The estimation of different precipitation phases using new detection theories and methods has become a research focus. Avariety of discrimination methods or schemes, such as the potential thickness threshold method of the air layer, the temperature threshold method of the characteristic layer, and the near-surface air temperature threshold method,have emerged one after another. Meanwhile, comparative studies on the discrimination accuracy and applicability assessment of multiple methods or schemes have also been carried out simultaneously. In recent years, the shift of precipitation from solid to liquid(SPSL) in the mid-to-high latitudes of the Northern Hemisphere has become more pronounced due to global warming and human activities. It leads to an increase in rain-on-snow(ROS) events and avalanche disasters, affecting the speed, intensity, and duration of spring snow-melting, accelerating sea ice and glacier melting, releasing carbon from permafrost, altering soil moisture, productivity, and phenological characteristics of ecosystems, and thereby affecting their structures, processes, qualities, and service functions. Although some progress has been made in the study of precipitation phases, there remains considerable research potential in terms of completeness of basic data, reliability of discrimination schemes, and the mechanistic understanding of the interaction between SPSL and other elements or systems. The study on shifts of precipitation phases and their impacts will play an increasingly important role in assessing the impacts of global climate change, water cycle processes,water resources management, snow and ice processes, snow and ice-related disasters, carbon emissions from permafrost, and ecosystem safety.
基金supported by the National Natural Science Foundation of China(Grant No.51576207)
文摘This study reports a new model of an air standard Dual-Miller cycle(DMC) with two polytropic processes and heat transfer loss.The two reversible adiabatic processes which could not be realized in practice are replaced with two polytropic processes in order to more accurately reflect the practical working performance. The heat transfer loss is taken into account. The expressions of power output, thermal efficiency, entropy generation rate(EGR) and ecological function are addressed using finite-time thermodynamic theory. Through numerical calculations, the influences of compression ratio, cut-off ratio and polytropic exponent on the performance are thermodynamically analyzed. The model can be simplified to other cycle models under specific conditions, which means the results have an certain universality and may be helpful in the design of practical heat engines. It is shown that the entropy generation minimization does not always lead to the best system performance.
文摘Software engineering is broadly discussed as falling far short of expectations. Data and examples are used to justify how software itself is often poor, how the engineering of software leaves much to be desired, and how research in software engineering has not made enough progress to help overcome these weaknesses. However, these data and examples are presented and interpreted in ways that are arguably imbalanced. This imbalance, usually taken at face value, may be distracting the field from making significant progress towards improving the effective engineering of software, a goal the entire community shares. Research dichotomies, which tend to pit one approach against another, often subtly hint that there is a best way to engineer software or a best way to perform research on software. This, too, may be distracting the field from important classes of progress.
基金financially supported by the National Natural Science Foundation of China (Nos. 50908144, 41173108)the Alexander von Humboldt Foundation (2010)+1 种基金The "Chenguang" project was supported by the Shanghai Municipal Education Commissionthe Shanghai Education Development Foundation (No. Z1126862)
文摘As one of the largest human activities, World Expo is an important source of anthropogenic Greenhouse Gas emission（GHG）, and the GHG emission and other environmental impacts of the Expo Shanghai 2010, where around 59,397 tons of waste was generated during 184 Expo running days, were assessed by life cycle assessment（LCA）. Two scenarios, i.e., the actual and expected figures of the waste sector, were assessed and compared, and 124.01 kg CO2-equivalent（CO2-eq.）, 4.43 kg SO2-eq., 4.88 kg NO-3-eq., and 3509 m3 water per ton tourist waste were found to be released in terms of global warming（GW）, acidification（AC）,nutrient enrichment（NE） and spoiled groundwater resources（SGWR）, respectively. The total GHG emission was around 3499 ton CO2-eq. from the waste sector in Expo Park, among which 86.47% was generated during the waste landfilling at the rate of 107.24 kg CO2-eq.,and CH4, CO and other hydrocarbons（HC） were the main contributors. If the waste sorting process had been implemented according to the plan scenario, around 497 ton CO2-eq.savings could have been attained. Unlike municipal solid waste, with more organic matter content, an incineration plant is more suitable for tourist waste disposal due to its high heating value, from the GHG reduction perspective.
